国际债券包括（）
A.固定利率债券和浮动利率债券
B.外国债券和欧洲债券
C.美元债券和日元债券
D.欧洲美元债券和欧元债券
参考答案：B
下列变化属于化学变化的是[ ]
A．钢铁腐蚀
B．玻璃破碎
C．铁杵成针
D．酒精挥发
—It's too difficult for you to answer.
—Why ____ the teacher for help?[ ]
A. don't ask
B. not ask
C. not wait
D. don't wait
